GRAND RAPIDS, MI -- If you plan to head out on the roads today, watch out for heavy fog in some areas.

The National Weather Service has issued a dense fog advisory for much of West Michigan, including Ottawa and Kent counties.

Visibility at the Gerald R. Ford Airport has been as low as one-quarter mile.

The fog comes with an extremely warm air mass over Michigan for early December. Temperatures will rise into the low 60s today, with a chance of thunderstorms later today.

By late Tuesday and Wednesday, reality will settle in, with temperatures back into the upper 30s for highs.

Here's the outlook:

Today A slight chance of showers, then a chance of showers and thunderstorms after 1 p.m. Areas of dense fog before 1 p.m. Otherwise, cloudy, with a high near 61. South southeast wind 9 to 16 mph. Chance of precipitation is 30 percent.

Tonight Showers likely and possibly a thunderstorm. Cloudy, with a low around 45. Breezy, with a south wind 15 to 22 mph becoming northwest after midnight. Chance of precipitation is 70 percent. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Tuesday Mostly sunny, with a high near 52. West wind 11 to 16 mph, with gusts as high as 25 mph.

Tuesday Night Partly cloudy, with a low around 29. West southwest wind 11 to 15 mph becoming north northwest after midnight.

Wednesday Mostly sunny, with a high near 39. North northwest wind 6 to 13 mph.